I found today's news article on Mariota surprising. https://dynastyleaguefootball.com/player-news?id=1884 The article states "Mariota currently occupies the QB9 slot in DLF's dynasty rankings but his 2017 ADP History shows an unsurprising decline in value from the start of the 2017 season. He concluded 2017 as the QB18 in fantasy."
I took this initially to mean he fell to 18 in ADP, but no, that must not be what the writer meant. Mariota actually fell from 5 to 9 in ADP. Still, looking at who is directly ahead of him—Luck, Newton, Prescott, Goff—I think he'll settle in soon enough around 5 or 6 again.
The "uncertainty" surrounding him now is infinitely better than the certainty surrounding him if Mularkey had remained his head coach. I cannot imagine the Titans didn't can Mularkey—and really, they canned him—precisely to go find someone who will better develop their star in the making QB. And so I respectfully disagree: Ain't no one gonna be buying him low off of me. Mariota still looks like a solid QB1 going forward, and I don't think anyone should react to a "down" year from a QB stuck in an unimaginative and conservative offense. MY only concern for Mariota is health, and I have that concern for everyone.

As a Mariota owner, i agree that no one is going to be buying him low off of me. I think a new coach does nothing but help his future and there is a good chance he bounces back and cements himself as a top 5-6 dynasty QB next year, if not better.

That doesn't mean I'm not concerned though... one of my priorities this off-season is to get a solid QB2 just in case the regression continues.